Introduction

Introduction

For my corpus I have decided to focus on famous cover songs. To me this is a very interesting topic because it shows how different people can expres the same song in such a way that it is fundamentaly diffent. It shows that the music, rythm, pitch, timbre, loudness and whatever else there might be introduced by an artist to expres a song has significant impact on the experience of a listener, even though the “story” told by the text is exactly the same.

As you will definitely notice through my corpus the originals in relation to their cover songs do not necessarily have a very easy way to be represented as groups. The reason for this is the fact that other than the versions of the same song, the songs are unrelated. Except of course for the fact that an maybe overly large portion of my songs was originally written by Bob Dylan. I have decided not to include any relationships between the Bob Dylan songs and the different covers, this is because I did not consider this to be the goal of this portfolio. However these considerations and the poor connection between the song do impact the validity of this corpus with respect to external factors.

A small issue other than the Bob Dylan presentation is the slight bias you would find in my corpus. Obviously over the years there have been countless songs with numerous covers, which are impossible to include, the ones that I’ve chosen are just the ones that I knew of and I enjoy. Therefore it is not necessarily a strong representation of originals and cover songs.")

---

Table of content:

Introduction
Tempo and Novelty
Waveform Analysis
Self Similarity
Pitch and Timbre Comparison
Some Chords
Machine Learning

First orientation and overview

---

To create an overview of the main differences between the songs I have connected them with an arrow. Using coloring, size and ggplotly it was not willing to draw all the lines, therefore I have included two plots, to show which songs are included and connected and one with more information about the actual songs. This plot shows the fist (general) overview of the songs in the corpus. The songs are quite spread, however we see a more dence cluster in the left quartile (0 < Valence <0.5 , 0 < Energy <0.5) meaning we have more slower/more “sad” songs.

A more connected overview

---

Here we have a little loss of information, however we gain insight in which way the songs (original and cover(s)) are related to each other. We can see that the Dancing in the moonlight versions for example differ quite a bit with regard to energy and valance, where the Resolution songs differ just a lot in energy, but have nearly the same valence. Intersting I think is the Knocking on heavens door connection, where we see between one version an increasing rise in valence and Energy between two others and both an increase in valence and energy between the first and last one (most left versus most right). Since we lost insight in Key and Tempo I will just tell you that the most right version is the Guns ’n Roses version, which is also in a different key than the two others. Considering this difference we will focus on these songs for the further portfolio.

Something else we will visit, is the Sound of Silence versions. These two are surprisingly close together. While the Simon and Garfunkel version sounds way more upbeat and happy to me. In general they have a total different feel to me.

A show of difference in distributions between original and cover versions regarding Tempo

---

A really interesting distribution difference here, the tempo’s are both centered around 120 bpm, however we see that the Original versions have a way earlier cut of around 85, where the Cover version go as far down as 65 bpm. The track this corresponds to is Make you Feel my Love by Adele (cover), which is interesting, because it is not the track with the lowest valence or energy, telling us that the spotify API does not necessarily consider tempo as the main factor for energy and valance. Therefore we will review this two for our two chosen songs.

Tempo analysis Guns ’n Roses

---

Even though the Bob Dylan version and the Eric Clapton version have a much slower feel that the Guns ’n Roses version, the tempograms do not seem to differ to much in BPM. I have tried verifying the tempo’s through Google because of this reason. The tempo estimations for the Bob Dylan version and the Guns ’n roses version seem to vary rather much somewhere between 65 and 140 bpm, however for the Eric Clapton version they seem pretty consistent. Which I thought was interesting considering this shows two pretty strong tempo “powers”. I think this might be caused by some rather silent percussion in the back, but I’m not sure of this. Something else I think is interesting to note is the tempo increase in the beginning and tempo decrease at the end in the Guns ’n Roses version, this change is clearly audible, which to me might be an indication that the estimations are rather accurate. Nonetheless these tempo estimations shown here are an interesting indication that the tempo more or less remained the same over the differnet cover versions.

Tempo Analysis Sound of Silence

---

the tempogram for the disturbed version looks really interesting as it is a little all over the place, but very clear around 80. Interesting as well is that it seems to be going up consistently. Why this is I am not sure. However the little up and down just over 200 seconds can be caused by the introduction of extra instruments and especially percussion, then after that there is a clear fade out. The tempogram for the Simon and Garfunkel version is really consistent and seems to be very accurate. There is no real surprises here. Also clearly a fade out at the end. What is surprising to me is the appearant accuracy of the estimation. The spotify API is more or less (if we would average this) spot on.

Novelty

---

Even though the grids vary (pay attention to different x and y scales), the degree of novelty does not seem to differ significantly between the versions. We see one outlier in the guns n roses graph that seems to marginalize the other values around 240. This is a little spike after a silent part, where they start singing “knock knock knocking” again. Other than that we see in general novelties with a maximum of 15. Especially in the Eric Clapton version. Which is expected since this is a rather consistent song.

Waveform analysis of Knocking on heavens door

---

As you can see I’ve included my waveform comparisons between different versions of Knocking on heavens door. I’ve chosen this one, because it shows absolutely no similarity what so ever. For the Bob Dylan version this makes sense as it is significantly shorter than the other version. However, the Eric Clapton version and the Guns ’N Roses version are very similar in duration. I think this is a very interesting representation on how different the “same” songs can be. Nonetheless listening to these songs, this is hardly surprising. Especially if we also take into consideration these songs are in different keys. will try to show this more with graphs in the future, as making waveform analysis for all songs is not feasible nor informative. I tried showing them in a rows overview, which is nicer, however because of the code that is shown this really messes up the overview.

Sound of Silence

---

As is clearly visible looking at the diagonal lines in both Chromagrams there is a significant amount of homogeneity in both versions. This is not very surpirsing, this is quite characteristic of the Simon and Garfunkel songs in generel. However intersting I believe is the massigve blocks visible in the Timbe graph for the disturbed version. In these blocks, there are some introduction of (quite strong) new percussion every now and then. Yet the Timbre seems to be dominated by the voice

Bob Dylan version

---

Some lines here

Eric Clapton version

---

Some text here

Guns ’n Roses version

---

Some lines here

Pitch for the Sound of Silence

---

I have decided just to include the pitch comparissons for the Sound Silence, as the one for Guns ’n Roses was more or less to be expected and we will revisit it when we look at the chords and keys. I assumed the pitches for the Sound of Silence version to be quite similar. Of course because of the similar keys, but also because in the beginning a guitar for the Simon and Garfunkel version and in the Disturbed version a piano quite distinctively playssimilar pitches.

First impression regarding timbre original and cover songs

---

We see that the distribution for the timbre features really is all over the place. The timbre for C01 and C02 are centered, and the at the end they seem to be more centered as well. As I have no clear interpretation of what these Timber features entail I’ll try to see if referring to this plot we can analyse the songs regarding to the rest of the Corpus.

Timbre for Sound of Silence

---

We see some expected behsviour….

Timbre for Knocking on Heavens door.

---

We can see a bigger magnitude for the Guns ’n Roses song in more pitches than for the other two songs. This is to be expected when listening to these songs. The guns n roses version has the most varriation in it, and actually sounds “biggest”. The clapton verson is much more calm and steady. Where the Dylan version is actual pretty quite and steady. Which is since its much smaller length also to be expected.

Some chords

---

I am currently working on a different way to extract the most dominant/stronger occuring chords from a variaty of sorts. If I manage this I will include this here, otherwise some extra chords graphs will be added from a variety of songs from the corpus.

Key analysis

---

Maybe even more interesting than the chords used in the different songs are the keys. As we know the Guns ‘n Roses version is one of the few songs in the corpus that differs in key from the original version. The difference in key is also clearly visible. Interesting I think is the that we can see that the Bob Dylan version and the Eric Claptoon version show very similar keys, but instead of showing a general G-major (relative E-minor) it shows a very strong appearance at Gb-major key (relative Eb-minor), which is in fact the F#-major that the Guns ’n Roses version is in, nonetheless the strength remains quite high at the actual G-major key. Similarly the Gb-major/D#-minor are present for the Guns’ n Roses version, but we see at least as strong magnitudes around C-minor and C#-minor. Considering the distance between these keys (in the circle of fifths) I am not entirely certain why the key-analyses shows this representation.

Classifier

---

My classifier trying to predict whether something is a original song or not does not do well at all. It has more or less a random accuracy. This is ofcourse not weird. There are no actual features that can predict whether the song is an original or not. We might include the date (which would of course be a very good indication) but this would nullafy the intention of the process, which is to see if there is a notable difference between original and cover songs. What might be an interesting feature to be added to the spotify API might be sound recording quality (if there could be such a measurement). This would probably be a good indication for when it was recorded and therefore for whether its a cover song or not.

Important feature analyses

---

As can be seen here I’ve chosen to extracted features that I consider to be meaningful to people and have left out the C#|D (which was impossible to use since r would consider it a comment) and went for more indicating features, which I’ve plotted in the second graph. As can be seen the features are all over the place, however we see some small clusters of just Covers and of just Originals. I am assuming that these smaller clusters are the reason that some of the classification was done correctly. Lets see if we have some more luck with the clustering!

# A tibble: 2 x 3
  class precision recall
  <fct>     <dbl>  <dbl>
1 No        0.529  0.692
2 Yes       0.467  0.304

Clustering

---

We can observe some of the songs to be in the same clusters. In general I think it would be a reasonable outcome of the clustering, most songs are in at least closely related clusters. I am not sure if this is a reasonable outcome, but I would say that it is the best we could have hoped for. Interesting is for example the All along the watchtower which is isolated at the bottom and very far away from the original version. Also interesting is looking back at the knocking on heavens door songs, where 2 have been clustered next to eachother (Dylan and Eric Clapton) but the third has been set apart (Guns ’n Roses). Which is not that strange since the diffent key used, as well as the different chords.